Source series termination (SST) adopted in a transmitter is configured by connecting an output driver, a termination resistor, and a signal line of the transmitter side in series and can transmit a signal having large amplitude (for example, 1000 mVdpp) at a high speed (for example, 10 Gbps or more). A transmitter (hereinafter, referred to as the “SST transmitter”) adopting the SST includes an output driver outputting a signal from a connection point of a first output circuit and a second output circuit each of which has a structure capable of changing a resistance value and output impedance of the output driver is varied.
The SST transmitter further includes a duplication driver. The duplication driver includes a first duplication circuit to be a duplication of the first output circuit and a second duplication circuit to be a duplication of the second output circuit. A circuit resistance value of the first duplication circuit is set to the same value as the resistance value of the first output circuit in cooperation with setting of the resistance value of the first output circuit and the first duplication circuit can output a first test voltage according to the set resistance value. In addition, a circuit resistance value of the second duplication circuit is set to the same value as the resistance value of the second output circuit in cooperation with setting of the resistance value of the second output circuit and the second duplication circuit can output a second test voltage according to the set resistance value.
In addition, in the SST transmitter, the resistance value of each of the first duplication circuit and the second duplication circuit is adjusted such that each of the first test voltage and the second test voltage approaches a target value or is within a target range. The resistance value of each of the first output circuit and the second output circuit is adjusted in cooperation with setting of the resistance value in each of the first duplication circuit and the second duplication circuit. As a result, the output impedance of the output driver is set to the target value or is set to be within the target range (refer to Patent Documents 1 and 2).